Could the reproductive system explain the stability and long-term persistence in a natural hybrid zone of Petunia (Solanaceae)?

Teixeira, Marcelo Costa; Turchetto, Caroline; Schnitzler, Carolina K.; Callegari-Jacques, Sídia M.; Freitas, Loreta B.

doi:10.1590/0102-33062020abb0514

Cited by 4 publications

(3 citation statements)

References 55 publications

(99 reference statements)

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“…In the two contact zones of P. axillaris and P. exserta , we identified individuals with varying degrees of interspecific admixture based on the analysis of genome-wide variation, ranging from individuals representing the pure species to intermediate interspecific hybrids. Notably, however, more than half of all 70 individuals analysed in this study proved to be (nearly) non-admixed representatives of either one of the two species, suggesting partial reproductive isolation of the species upon secondary contact [ 47 , 48 , 53 ].…”

Section: Discussionmentioning

confidence: 98%

“…A recent study estimated this secondary contact of the species to be recent (approximately 920 years ago) and ongoing [ 45 ]. Although interspecific hybrids can produce viable offspring and can be found within the hybrid zones, individuals displaying the pure P. axillaris and P. exserta phenotypes are found at relatively high frequency [ 44 , 46 – 48 ]. This suggests partial reproductive isolation between the species upon secondary contact, likely due to their different pollination syndromes [ 45 , 49 – 52 ].…”

Section: Introductionmentioning

confidence: 99%

Genetic architecture of a pollinator shift and its fate in secondary hybrid zones of two Petunia species

et al. 2023

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Background Theory suggests that the genetic architecture of traits under divergent natural selection influences how easily reproductive barriers evolve and are maintained between species. Divergently selected traits with a simple genetic architecture (few loci with major phenotypic effects) should facilitate the establishment and maintenance of reproductive isolation between species that are still connected by some gene flow. While empirical support for this idea appears to be mixed, most studies test the influence of trait architectures on reproductive isolation only indirectly. Petunia plant species are, in part, reproductively isolated by their different pollinators. To investigate the genetic causes and consequences of this ecological isolation, we deciphered the genetic architecture of three floral pollination syndrome traits in naturally occurring hybrids between the widespread Petunia axillaris and the highly endemic and endangered P. exserta. Results Using population genetics, Bayesian linear mixed modelling and genome-wide association studies, we found that the three pollination syndrome traits vary in genetic architecture. Few genome regions explain a majority of the variation in flavonol content (defining UV floral colour) and strongly predict the trait value in hybrids irrespective of interspecific admixture in the rest of their genomes. In contrast, variation in pistil exsertion and anthocyanin content (defining visible floral colour) is controlled by many genome-wide loci. Opposite to flavonol content, the genome-wide proportion of admixture between the two species predicts trait values in their hybrids. Finally, the genome regions strongly associated with the traits do not show extreme divergence between individuals representing the two species, suggesting that divergent selection on these genome regions is relatively weak within their contact zones. Conclusions Among the traits analysed, those with a more complex genetic architecture are best maintained in association with the species upon their secondary contact. We propose that this maintained genotype–phenotype association is a coincidental consequence of the complex genetic architectures of these traits: some of their many underlying small-effect loci are likely to be coincidentally linked with the actual barrier loci keeping these species partially isolated upon secondary contact. Hence, the genetic architecture of a trait seems to matter for the outcome of hybridization not only then when the trait itself is under selection.

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“…Under reinforcement theory, pre- and postzygotic barriers to geneflow establish or maintain species identities through processes such as physical incompatibilities, hybrid infertility, and reduced hybrid fitness (Servedio and Noor 2003). In their excellent review, Servedio and Noor (2003) note that reinforcement has been demonstrated empirically and theoretically in numerous systems (for recent examples see Groh and Cronk 2020, O'Brien et al 2021, Punzalan et al 2021, Teixeira et al 2021), but note that there is a lack of temporal studies that examine reinforcement over multiple generations (but see Pfennig and Simovich 2002, Pfennig et al 2016). In addition, there have been few studies that have examined reinforcement in the context of species invasions (but see Irimia et al 2021, (Sirkia et al 2018) though it has been discussed in a biological control context (see Fischer et al 2015), which in many regards is very similar to a species invasion context (Schulz et al 2021).…”

Section: Introductionmentioning

confidence: 99%

Seasonal differences in the timing of flight between the invasive winter moth and native Bruce spanworm promotes reproductive isolation

Andersen

Havill

Chandler

et al. 2023

Environmental Entomology

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The European winter moth, Operophtera brumata L. (Lepidoptera: Geometridae), was accidentally introduced to North America on at least 4 separate occasions, where it has been hybridizing with the native Bruce spanworm, O. bruceata Hulst, at rates up to 10% per year. Both species are known to respond to the same sex pheromones and to produce viable offspring, but whether they differ in the seasonal timing of their mating flights is unknown. Therefore, we collected adult male moths weekly along 2 transects in the northeastern United States and genotyped individuals using polymorphic microsatellite markers as males of these 2 species cannot be differentiated morphologically. Along each transect, we then estimated the cumulative proportions (i.e., the number of individuals out of the total collected) of each species on each calendar day. Our results indicate that there are significant differences between the species regarding their seasonal timing of flight, and these allochronic differences likely are acting to promote reproductive isolation between these 2 species. Lastly, our results suggest that the later flight observed by winter moth compared to Bruce spanworm may be limiting its inland spread in the northeastern United States because of increased exposure to extreme winter events.

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Could the reproductive system explain the stability and long-term persistence in a natural hybrid zone of Petunia (Solanaceae)?

Cited by 4 publications

References 55 publications

Genetic architecture of a pollinator shift and its fate in secondary hybrid zones of two Petunia species

Seasonal differences in the timing of flight between the invasive winter moth and native Bruce spanworm promotes reproductive isolation

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